There are a number of different devices and methods for measuring, calculating or estimating the heart rate of a person. For example, heart rate monitors and similar wristop computers may include a transmitter belt attached to the human body by a flexible belt for detecting the heartbeat. Heartbeat detection may e.g. take place during motion of the person. The detection device equipped with electrodes transmits measurement data wirelessly to e.g. a wristwatch-like wristop computer, in which at least a part of the received signal is processed and displayed on the display of the wristop computer.
Heartbeat detection may be arranged by a topology in which signal derived from electrodes is amplified and filtered before analog-to-digital (AD) conversion. The digital signal is then provided for digital processing for heartbeat detection. However, since the analogue signal comprises disturbance, considerable digital signal processing may be required to recover appropriate data for heartbeat detection. Analogue electronics may be applied to process the analogue signal for removing disturbance.
US2014/0163386 discloses a circuit and method for electrocardiogram (ECG) monitoring. The method comprises: amplifying a signal from a signal source to form an amplified signal; amplifying the amplified signal with an amplifier having a bandwidth sufficient to form a filtered amplified signal with highest frequency pulsatile features of amplified signal preserved; amplifying the amplified signal with an amplifier having a bandwidth sufficient to preserve the baseline while removing the pulsatile components; adding a DC offset to the baseline to form an offset baseline; comparing the filtered amplified signal to the offset baseline; and generating an output signal if the filtered amplified signal is greater than the offset baseline.